This invention relates generally to an improved flow control valve. More particularly, but not by way of limitation, this invention relates to an improved flow control valve having a single inlet and a pair of outlets with flow, in one operating position, being restricted and through one of said outlets, in a second operating position being restricted and through both of said outlets, and in a third operating position, being substantially unrestricted and through only one of said outlets.
As previously mentioned, the improved flow control valve of this invention is particularly suited for use in decoking operations. In the last phase of refining petroleum products, the remaining petroleum is pumped into extremely large tanks and elevated to temperatures sufficient to drive off all of the remaining volatile materials. The residue remaining in the tank after heating is substantially pure coke. To remove the coke from the tank the practice is to pump water which is at high pressure and in relatively large volumes, through nozzles located in the tank to disintegrate the coke. For example, a pump delivering water to the nozzles may be supplying the water and 2,000 gals. of water per minute and at approximately 3,000 lbs. per sq. in. pressure.
The pumps are generally driven by electric motors and may require as much as 4,000 horsepower. With such large motors it is not practical to stop the pump and motor each time it is necessary to change a nozzle or perform other operations in the tank which require discontinuation of the water flow. Therefore, it has been the practice in the past to provide several valves that are connected with each other and with the pump and arranged to provide for bypass flow when the main flow is stopped without stopping the pump and motor.
Also, because of the relatively large hoses, pipes, etc. connecting the pump with the nozzles, it is desirable to fill the pipes relatively slowly to prevent "water hammer" which could result in destruction of the system. The necessary valves and external pipes mentioned above have also provided this function.
An object of this invention is to provide an improved flow control valve which, through the medium of a single multipurpose valve can provide all of the foregoing desirable features.